This invention relates generally to a method for treating or studying a cardiovascular condition of a patient by employing a vascular interventional device that may be introduced over a guidewire into a vessel of the cardiovascular system of a patient. More particularly, the invention relates to use of a vascular interventional device that functions both as a vascular entry sheath and as a diagnostic or therapeutic catheter. Such a device is capable of delivering both diagnostic and/or therapeutic agents, as well as other interventional devices, to a specific target portion of the cardiovascular system of a patient.
As used herein, a vascular interventional device or interventional device is any device that may be passed through a portion of the cardiovascular system of a patient for diagnostic or therapeutic purposes, including diagnostic and therapeutic catheters. The term also includes components of such devices and other instruments that may be used to facilitate the passage of such devices within the cardiovascular system, such as guidewires, dilators and sheaths.
As used herein, a patient may be a human or another mammal.
As used herein, vessels of the cardiovascular system of a patient or blood vessels include arteries and veins and branches thereof or therefrom, and other tubes, chambers and ducts that carry blood.
As used herein, a vessel of entry is a vessel that is entered from outside the body of the patient.
As used herein, a target vessel or branch of a vessel is a portion of the cardiovascular system of a patient that is targeted for diagnosis or therapy, or that provides a pathway to such portion from a vessel of entry. A target vessel may also be a vessel of entry.
As used herein, a vascular segment is a portion of a vessel.
As used herein, a vascular interventional device or a component thereof may be adapted to selectively engage a target vessel or branch of a vessel. Such a device or component may be shaped, formed or manipulated so that when it is advanced to a location adjacent to the target vessel or branch, further advancement will cause the distal end of the device to enter the target vessel or branch.
As used herein, a guidewire is a device that may be used in positioning and moving a diagnostic or therapeutic vascular interventional device.
As used herein, a sheath is a tube that may be used to facilitate the passage of a vascular interventional device within the cardiovascular system of a patient.
As used herein, a dilator is a vascular interventional device or a component thereof that may be used to dilate a portion of one or more vessels of the cardiovascular system so as to facilitate entry or passage of another vascular interventional device or component thereof.
As used herein, a catheter is a vascular interventional device that may be used for diagnostic or therapeutic purposes.
As used herein, a fluid agent is a drug or other fluid that may be injected into a portion of the cardiovascular system for therapeutic or diagnostic purposes.
As used herein, a fluid agent is delivered to a target portion of the cardiovascular system of a patient at a clinically effective rate or an effective rate when said agent is delivered at a flow rate that is suitable for the effective use of the fluid agent and at a velocity that is unlikely to cause injury or damage to the target portion of the cardiovascular system.
As used herein, a contrast agent, medium or fluid is a radiopaque fluid agent that may be used to provide a contrast in density with tissue, structures or another object for x-ray or other radiological examination.
As used herein, the French scale is a measurement system that may be used to indicate the diameter of a vascular interventional device or a component thereof. Each unit on the scale is equal to 1/xcfx80 millimeters.
In conventional practice, access to a vessel of the cardiovascular system of a patient may be obtained using a vascular entry sheath. Generally, a needle is used to puncture a blood vessel of entry (such as an artery), and a guidewire is passed through the needle to a desired location in the vessel. The needle is withdrawn and the guidewire is maintained in position in the vessel. Then a short sheath is advanced into the vessel over the guidewire to facilitate introduction of a diagnostic or therapeutic catheter. A catheter is advanced through the sheath, and the guidewire may then be removed. Once the distal end of the catheter is advanced to the target vessel, diagnostic or therapeutic procedures may be carried out. Depending on the type of catheter employed, fluid agents may be injected through the catheter for diagnostic or therapeutic purposes. However, if it is necessary or desirable to inject an x-ray contrast agent into a target vessel, a large caliber catheter must be advanced through the sheath to the target vessel, so as to provide for sufficiently high flow rates to displace blood with contrast agent. In most cases, the sheath itself may not serve as the conduit for delivery of contrast agent because conventional sheaths are usually quite short and are not adapted to selectively engage a vessel of the cardiovascular system. Furthermore, conventional sheaths have only a single end hole, and fluid injected therethrough in volumes sufficient for a contrast agent would likely flow from the end hole at such a velocity that tissue damage might occur. Consequently, a conventional sheath is used only to provide access to the vessel of entry, and a catheter is advanced through the sheath to reach a target vessel. If it is desired to deliver a fluid agent such as contrast fluid to a segment of the target vessel, it is generally necessary to employ a diagnostic catheter. If it is desired, after imaging of the target area, to employ another therapeutic or diagnostic device, the diagnostic catheter must first be removed, so that a second interventional device may be advanced to the target area.
Various catheters for distribution of fluid agents (sometimes referred to as infusion catheters) are known. For example, U.S. Pat. No. 5,021,044 of Sharkawy describes a vascular catheter having an inner lumen for receiving a guidewire and at least one concentrically disposed outer lumen for delivery of a fluid agent. The outer lumen is provided with a number of flow passageways to maintain a desired flow pattern to the target site, typically of about 0.1-1.5 cm3/hour. U.S. Pat. No. 5,599,324 of McAlister et al. and U.S. Pat. No. 5,709,874 of Hanson et al. describe similar multi-lumen catheters. U.S. Pat. No. 5,380,307 of Chee et al. and U.S. Pat. No. 5,425,723 of Wang describe perfusion catheters that are designed to deliver a fluid agent through side holes uniformly along a perfusion portion of the catheter. These devices operate to deliver fluid to a target point within a vessel at low flow rates that are useful for introduction of pharmacological agents such as thrombolytic drugs, but are wholly insufficient for proper introduction of a contrast agent. Furthermore, these devices do not accommodate or facilitate the introduction of a second interventional device into the cardiovascular system of a patient.
U.S. Pat. No. 5,569,197 of Helmus et al. describes a hollow infusion guidewire over which a catheter may be introduced into a vessel. Preferably, the Helmus guidewire has an outer diameter that is comparable to that of a standard coronary guidewire, typically about 0.014 inch. It also has a plurality of openings or perforations in the sidewall near its distal end for dispersal of a drug therethrough. However, since it is sized to function as a guidewire too, it may only be used to disperse fluid at the target location at a very low rate, thereby limiting its use to the delivery of drugs only.
Many of the known infusion guidewires include complicated multi-lumenal structures and valve arrangements that are difficult and expensive to manufacture. Furthermore, these devices generally operate to deliver fluid agents to a target site at low flow rates that are wholly insufficient for use in delivering contrast media. Other devices that may be employed to deliver contrast media at an appropriate rate permit flow at a velocity that is likely to cause tissue damage. Thus, for example, U.S. Pat. No. 5,180,364 of Ginsburg describes a self-perfusing guiding catheter that is adapted for delivery of contrast media through a central lumen. The catheter includes a number of holes or slits that are provided with one-way valves so as to selectively permit fluid communication between the central lumen and the exterior of the device. When contrast media is injected through the central lumen, the valves close so that all of the contrast fluid is delivered out the end of the device. When no fluid is injected, the valves open to prevent the device from blocking blood flow within the vessel by permitting perfusing blood to flow into and through the catheter. After imaging of the target area is obtained, as by radiographic examination of the contrast media, a second catheter may be introduced through the central lumen and advanced to the target area. However, when the Ginsburg device is used to deliver a significant volume of contrast fluid in order to displace blood volume, the velocity of delivery of contrast fluid out the end hole may be so great that tissue damage may occur.
It would be desirable therefore if a vascular interventional device were developed that could be used to deliver fluid such as contrast media to a target area at a rate sufficient to displace blood so that a radiologic examination of the target area could provide useful information, but at a velocity that would minimize tissue damage. It would also be desirable if such a device were developed that could be used to deliver fluid at an effective rate while a second interventional device was being used to diagnose or treat a condition.
Accordingly, it is an advantage of the invention claimed herein to provide a method for treating or studying a cardiovascular condition of a patient. It is also an advantage of the invention to provide such a method which may employ a first vascular interventional device to deliver a second interventional device to a target vessel or vessel segment so that the second device may be used for therapeutic or diagnostic purposes while a fluid agent is being delivered at a clinically effective rate through the first device. It is yet another advantage of the invention to provide a method to measure the difference in blood pressure (if any) across a vascular segment of the cardiovascular system of a patient.
Additional advantages of this invention will become apparent from an examination of the drawings and the ensuing description.
The invention comprises a method for treating or studying a cardiovascular condition of a patient, using two vascular interventional devices, at least one of which (a first vascular interventional device) includes a hollow, flexible tube having a proximal end and a distal end, and a lumen that is continuous from the proximal to the distal end. In a preferred embodiment of the first vascular interventional device, the flexible tube includes a plurality of side holes near the distal end, each of which is in continuous fluid communication with the lumen. The distal end of the tube is adapted to selectively engage a target vessel of the cardiovascular system of the patient. The first vascular interventional device also includes a hollow vessel dilator that is adapted for insertion into and through the tube and over the guidewire. The dilator has an inside diameter that is slightly larger than the guidewire, and an outside diameter that is slightly smaller than the diameter of the lumen of the tube. The distal end of the dilator is tapered to accommodate vascular entry over the guidewire. The dilator is adapted to dilate the vessel to accept the tube. The first vascular interventional device also includes a hub at the proximal end of the tube. The hub includes an end port through which a second interventional device having an outside diameter smaller than the diameter of the lumen (including a second interventional device having a pressure transducer connected thereto) may be introduced into and through the lumen of the tube. The hub also includes a side port through which a fluid agent may be injected for delivery through the lumen and out the end hole (and in a preferred embodiment of the invention, out the side holes of the tube) or through which pressures can be measured, using a pressure transducer that may be connected thereto. A sealing mechanism is also provided in the hub to prevent air from entering the tube and blood and other fluids from leaking out of the tube through the hub. According to the method, a guidewire is inserted into a vessel of the cardiovascular system of a patient in the conventional manner. The dilator of the first device is then inserted into the tube with its distal end protruding from the distal end of the tube. The dilator and tube are then inserted into the vessel over the guidewire and positioned in the target area. The dilator is then withdrawn through the tube from the cardiovascular system of the patient. A second interventional device is selected to treat or study the cardiovascular condition, and the second device is introduced through the end port of the hub of the first device. The second interventional device is advanced over the guidewire to the distal end of the tube of the first device, and the guidewire is then removed. A fluid agent is then injected through the side port for delivery through the lumen around the second vascular interventional device, and out the end hole (and, in a preferred embodiment, out the side holes) of the tube. The second interventional device is employed to treat or study the cardiovascular condition.
The invention also includes a method for using a pair of vascular interventional devices to measure the difference in blood pressures across a vascular segment of the cardiovascular system of a patient. The method includes providing a first vascular interventional device that includes a hollow, flexible tube, a hub and a dilator, as described above. A guidewire is inserted into a vessel of the cardiovascular system of a patient in the conventional manner. The dilator of the first device is then inserted into the tube with its distal end protruding from the distal end of the tube. The dilator and tube are then inserted into the vessel over the guidewire and the distal end of the tube is positioned at a first location in the target area. The dilator is then withdrawn from the cardiovascular system of the patient and is removed from the tube. A first pressure transducer is attached to the side port of the first device. A second interventional device, which is suitable for use in measuring the blood pressure at a point in the cardiovascular system, is selected and introduced through the end port of the hub of the first device. The second interventional device is advanced over the guidewire so that its distal end is located at a second location beyond the first location (beyond the distal end of the tube of the first device). The guidewire is then removed, and a second pressure transducer is attached to the proximal end of the second interventional device. The blood pressure is then measured simultaneously at the distal end of the tube of the first interventional device (the first location) and at the distal end of the second interventional device (the second location). The difference in blood pressure, if any, between the first and second locations is then calculated.
In order to facilitate an understanding of the invention, the preferred embodiments of the invention are illustrated in the drawings, and a detailed description thereof follows. It is not intended, however, that the invention be limited to the particular embodiments described or to use in connection with the apparatus illustrated herein. Various modifications and alternative embodiments such as would ordinarily occur to one skilled in the art to which the invention relates are also contemplated and included within the scope of the invention described and claimed herein.